Electrical appliance and power supply thereof

1. Technical Field

Embodiments of the present disclosure relate to electrical appliances, and particularly to a power supply of an electrical appliance.

2. Description of Related Art

Electrical appliances, such as large liquid crystal displays (LCDs) and televisions, are powered by the mains power (also known as household power, grid power, etc.). Most current electrical appliances include a power supply to convert alternating current (AC) voltages of the mains power into direct current (DC) operative voltages to power components of the electrical appliances. Such power supply typically includes a rectifier and a capacitor. The rectifier converts the AC voltage to the DC voltage, and the capacitor filters out interferences and smoothes the DC voltage. However, the capacitor discharges slowly when the electrical appliances are power off or changed into a power saving mode (only part of the components of the electrical appliances are shut down). Thus taking a long time to shut down the electrical appliances or getting into the power saving mode. This is an inconvenience.

Therefore, an improved power supply for an electrical appliance is needed that addresses the limitations described.

Many aspects of the embodiments can be better understood with references to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a block diagram of an electrical appliance including a power supply in accordance with one embodiment of the present disclosure, the power supply includes a delay module.

FIG. 2 is a schematic diagram of one embodiment the delay module of FIG. 1 .

Referring to FIG. 1 , an electrical appliance 999 in accordance with one embodiment is shown. The electrical appliance 999 may be a liquid crystal display (LCD), a television, a desktop computer, or a media player. The electrical appliance 999 includes a power supply 100 , a control unit 200 , and a load 300 . Understandably, the load 300 may include a display panel and various processing circuits (not shown). The control unit 200 is operable to control operations of the load 300 .

The power supply 100 is operable to receive input voltage from an external power supply/source 400 , and supply a first operation voltage to the load 300 and a second operation voltage to the control unit 200 . The power supply 100 supplies continuous power to the second operation voltage to the control unit 200 for a predetermined time period after the electrical appliance 999 is shut down or after the electrical appliance 999 enters a power saving mode. In the power saving mode, the power supply 100 stops receiving power from the external power supply/source 400 , while other components, such as a control chip, of the electrical appliance 999 may still be powered by the external power supply/source 400 . In the embodiment, the external power supply/source 400 is the mains power that supplies an alternating current (AC) voltage.

The power supply 100 includes an adapter 110 and a delay module 120 . The adapter 110 includes a rectifier 111 and one or more filter capacitors 112 . The rectifier 111 is operable to convert the input voltage from the external power supply/source 400 to the first operation voltage. The one or more filter capacitors 112 are configured to filter out interferences and smooth the first operation voltage.

The delay module 120 is configured to detect the input voltage from the external power supply/source 400 , and supply the second operation voltage to the control unit 200 when receiving the input voltage from the external power supply/source 400 , and continue supplying the second operation voltage to the control unit 200 over/during the predetermined time period after the input voltage is removed. As a result, after the input voltage is removed, the control unit 200 continues controlling the load 300 according to the discharge of the one or more filter capacitors 112 . Thus the one or more filter capacitors 112 can discharge rapidly, and the electrical appliance 999 can shut off or enter the power saving mode instantly.

To achieve the above goal, further referring to FIG. 2 , the delay module 120 in one embodiment includes a detect circuit 121 , a sub power supply 122 , a control circuit 123 , and an output circuit 124 . The detect circuit 121 is configured to generate a first signal when receiving the input voltage, and a second signal when the input voltage is removed. The first signal is used to signal the control circuit 123 that the input voltage is applied to the load 300 , and the second signal is used to signal the control circuit 123 the input voltage is no longer supplied to the load 300 . The detect circuit 121 includes a first resistor R 1 , a first capacitor C 1 , and a first switching component Q 1 . A terminal of the first resistor R 1 is connected to the external power supply/source 400 to receive the input voltage, and the other terminal of the first resistor R 1 is connected to a terminal of the first capacitor C 1 and the base of the first switching component Q 1 . The other terminal of the first capacitor C 1 and the emitter of the first switching component Q 1 are grounded. The collector of the first switching component Q 1 is connected to the control circuit 123 . In the embodiment, the first switching component Q 1 is an NPN type bipolar junction transistor (BJT).

The sub power supply 122 is operable to supply the second operation voltage to the control circuit 123 and the output circuit 124 .

The control circuit 123 is configured to control the output circuit 124 to output the second operation voltage when receiving the first signal, and further control the output circuit 124 to continue outputting the second operation voltage for the predetermined time period when receiving the second signal. The control circuit 123 includes a second resistor R 2 , a third resistor R 3 , a fourth resistor R 4 , a second capacitor C 2 , a second switching component Q 2 , and a diode D. In the embodiment, the diode D is a Zener diode. One terminal of the second resistor R 2 is connected to the collector of the first switching component Q 1 . The other terminal of the second resistor R 2 is connected to a terminal of the second capacitor C 2 , the cathode of the diode D, and a terminal of the third resistor R 3 . The other terminal of the second capacitor C 2 is grounded. The anode of the diode D is connected to the base of the second switching component Q 2 via the fourth resistor R 4 . The emitter of the second switching component Q 2 is connected to the sub power supply 122 to receive the second operation voltage, and further connected to the other terminal of the third resistor R 3 . The collector of the second switching component Q 2 is connected to the output circuit 124 . The second switching component Q 2 is a PNP type BJT. A resistance of the third resistor R 3 is greater than that of the second resistor R 2 .

The output unit 124 includes a fifth resistor R 5 , a sixth resistor R 6 , a seventh resistor R 7 , a third switching component Q 3 , and a photo coupler U. The photo coupler U includes a light-emitting diode (LED) U 11 and a phototransistor U 12 . The terminal of the fifth resistor R 5 is connected to the control circuit 123 , and the other terminal of the fifth resistor R 5 is connected to the anode of the LED U 11 . The cathode of the LED U 11 is grounded. The emitter of the phototransistor U 12 is grounded. The collector of the phototransistor U 12 is connected to the base of the third switching component Q 3 via the sixth resistor R 6 . The seventh resistor R 7 is connected between the base and the emitter of the third switching component Q 3 . The emitter of the third switching component Q 3 is connected to the sub power supply 122 to receive the second operation voltage, and the collector of the third switching component Q 3 is configured to output the second operation voltage. The third switching component Q 3 is a PNP type BJT.

In operation, when the power supply 100 receives the input voltage, the first switching component Q 1 is turned on, and the sub power supply 122 starts outputting the second operation voltage. A voltage at the node between the second and third resistors R 2 , R 3 (the voltage at the second capacitor C 2 ) is a low level voltage, and the diode D and the second switching component Q 2 are turned on. Thus the second operation voltage is transmitted to the output circuit 124 via the control circuit 123 . Accordingly, the LED U 11 is turned on. The phototransistor U 12 is turned on, thus a voltage at the base of the third switching component Q 3 becomes a low level voltage. The third switching component Q 3 is turned on and transmits the second operation voltage to the control unit 200 .

When the input voltage is no longer supplied to the power supply 100 and the load 300 , the first switching component Q 1 is turned off, the adapter 110 stops operating, and the sub power supply 122 continues outputting the second operation voltage to the control unit 200 . Accordingly, the second capacitor C 2 is charged by the sub power supply 122 via the third resistor R 3 . The load 300 continues operating under control of the control unit 200 , and the one or more filter capacitors 112 start discharging via the load 300 rapidly. Thus, the electrical appliance 999 can shut off or enter the power saving mode instantly.

After the predetermined time period, the voltage at the second capacitor C 2 becomes a high level voltage. Accordingly, the diode D is Zener broken down, the second switching component Q 2 is turned off. Thus the photo coupler U is turned off, and the voltage at the base of the third switching component Q 3 becomes a high level voltage (equal to the second operation voltage). The third switching component Q 3 is turned off and stops transmitting the second operation voltage to the control unit 200 .

It is to be understood, however, that even though numerous characteristics and advantages of the present disclosure have been set forth in the foregoing description, together with details of the structure and function of the disclosure, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.